The present invention relates to a communications system that uses a mobile phone network and an IP (Internet Protocol) network.
In a mobile phone network, e.g., in a Third Generation mobile phone network, there are areas which are geographically within the service area (the area within which radio waves from base stations reach) but where the reception of radio waves involves difficulties (such areas are called insensible areas). This is because it is occasionally difficult to sufficiently receive radio waves from base stations behind or within buildings or underground, since radio waves basically travel straight.
Such insensible areas include the interiors of buildings, specifically the interiors of individuals' homes, such as detached homes or apartment houses. It is therefore demanded to provide small-sized base stations within the homes of individuals so that radio waves from the mobile phone network can be smoothly received in the homes.
Background arts related to the present invention include the techniques described in the Patent documents 1 and 2 below, for example:                [Patent document 1] JP 2004-507946 A        [Patent document 2] JP 2002-535888 A        